"""Campaign VM VM6 — robust foliage-wind pixel proof.

Usage: py tools/vm6/wind-pixel-proof.py <capture-root>

<capture-root> holds four run-offline-pixel-gate.ps1 output directories,
all at the SAME ACDREAM_SKY_PHASE_SECONDS pin and sun-shadow-strength=0:
  amp-t3, amp-t3b        wind on (amplified or default strength)
  nowind-t3a, nowind-t3b wind-enabled=false
Each directory contains screenshots/world-offline.png.

Why four captures: the same binary/settings/pin differs run-to-run by 0 or
~280 isolated leaf-edge pixels (rasterisation flips along the treeline), so a
single on-vs-off pair cannot be trusted. The repeat pairs measure that floor;
the robust mask is the AND of all four cross pairs minus both repeat pairs.
See docs/research/2026-08-23-vm6-foliage-wind-pixel-proof.md.
"""
import sys
import numpy as np
from PIL import Image

root = sys.argv[1]
threshold = int(sys.argv[2]) if len(sys.argv) > 2 else 8


def load(name):
    return np.asarray(
        Image.open(f"{root}/{name}/screenshots/world-offline.png").convert("RGB")
    ).astype(int)


def strong(a, b):
    return np.abs(a - b).max(axis=2) >= threshold


def bands(mask):
    ys, _ = np.nonzero(mask)
    return np.bincount(ys // 60, minlength=12).tolist() if len(ys) else [0] * 12


A, B, N1, N2 = load("amp-t3"), load("amp-t3b"), load("nowind-t3a"), load("nowind-t3b")
noise = strong(N1, N2)
repeat = strong(A, B)
print(f"threshold |d|>={threshold}")
print("floor     wind-off A vs B :", int(noise.sum()), bands(noise))
print("repeat    wind-on  A vs B :", int(repeat.sum()), bands(repeat))
for name, (x, y) in {
    "wind-on A vs off A": (A, N1),
    "wind-on A vs off B": (A, N2),
    "wind-on B vs off A": (B, N1),
    "wind-on B vs off B": (B, N2),
}.items():
    m = strong(x, y)
    print(f"{name:20s}: {int(m.sum()):6d} {bands(m)}")
robust = strong(A, N1) & strong(A, N2) & strong(B, N1) & strong(B, N2) & ~noise & ~repeat
print("ROBUST wind mask      :", int(robust.sum()), bands(robust))
out = A.copy()
out[robust] = [255, 0, 0]
Image.fromarray(out.astype(np.uint8)).save(f"{root}/diff-robust-wind.png")
print(f"overlay: {root}/diff-robust-wind.png")